Školjka Let 
be positive integers. Consider in a plane 
two disjoint sets of points 
and 
consisting of 
and 
points, respectively, and such that no three points of the union 
are collinear. Prove that there exists a straightline 
with the following property: Each of the two half-planes determined by on ( not being included in either) contains exactly half of the points of and exactly half of the points of 
be positive integers. Consider in a plane two disjoint sets of points and consisting of and points, respectively, and such that no three points of the union are collinear. Prove that there exists a straightline with the following property: Each of the two half-planes determined by on ( not being included in either) contains exactly half of the points of and exactly half of the points of